import numpy as np

def S2Beta_3(Signal_para, Fiber_para):
    D = Fiber_para["D"]
    lamda = Fiber_para["lambda"]
    C = Signal_para["C"]
    S = Fiber_para["S"]

    Beta_3 = (lamda / (2 * np.pi * C))**2 * (2 * lamda * D + lamda**2 * S) * 1e-30

    return Beta_3
